1. Field of the Invention
The present invention relates to a process for production of a semiconductor light-emitting device in which an improved relief structure is formed on the light-extraction surface, and also relates to the semiconductor light-emitting device produced thereby.
2. Description of Related Art
For the purpose of improving the light-extraction efficiency of a semiconductor light-emitting device such as a light-emitting diode (LED), it has hitherto been proposed to form a relief structure on the light-extraction surface of the device by use of a self-assembled block copolymer film as a mask (see, Patent documents 1, 2).
The relief structure is generally formed after an electrode is provided on the light-extraction surface. Specifically, first a self-assembled film is formed by spin-coating on the light-extraction surface previously provided with an electrode thereon, and then the light-extraction surface is dry-etched through the pattern of self-assembling as a mask to form a relief structure. However, since the electrode normally has a thickness of 1 μm or more, the self-assembled film formed thereover by spin-coating has a large step around the electrode and hence the film in the area covering around the electrode is locally thicker than the designed thickness. Because of this locally large thickness, the self-assembling pattern in the area around the electrode cannot be transferred onto the light-extraction surface, and consequently the relief structure is formed in a smaller area. In particular, considering that the area around the electrode generally gives off intense luminescence, it is a critical problem that the relief structure cannot be formed there. There is thus room for improvement in luminance of the device.
JP-A 2007-220865 (KOKAI) describes a method in which a relief structure is previously formed by photolithography on the light-extraction surface and thereafter an electrode is provided thereon. This method enables to form the relief structure in the area near the electrode. However, if the light-extraction surface contains semiconductors of high etching rates such as GaAs, the method cannot form a good relief structure.